Re: A Schiefspiegler as first telescope (was Re: ATM 3-Vane or 4-Vane Spiders)

["Richard" <richas@earthlink.net>]

Perfect?   Perfect for what?   It all depends on your application.  For
example, if you are doing prime focus photography or if you are taking your
telescope to the mountains in your small car, f/4 is much better than f/6,
especially with a field corrector lens.   If you are trying to resolve
double stars or see planetary detail, f/11 is much better than f/6.

Your f/6 telescope, with an oversized diagonal and a rather large eyepiece
might well do a good job on faint fuzzies.   If budget is a consideration,
the charts in R & vanV show ordinary eyepieces working poorly with light
cones fatter than f/5.6.  The f/4 photographic scope will require a very
expensive eyepiece if it is to be used visually.

One size does NOT fit all.  We originally settled on f/8 back in the
pre-Hitler era because experts who mandated everything did not consider that
different jobs might require different tools.

. . . Richard


----- Original Message -----
From: "Joe Mayenschein" <mayen1@mwt.net>
To: "Ken Hunter" <kb7h@onemain.com>
Cc: "Charvell" <charvell@sofnet.com>; <atm@shore.net>
Sent: Saturday, October 06, 2001 6:10 AM
Subject: Re: A Schiefspiegler as first telescope (was Re: ATM 3-Vane or
4-Vane Spiders)


>
> I always thought the f-6 was the perfect f ratio myself.  Fast enough for
decent
> faint fuzzies or even photography, yet long enough for decent high power
> planetary viewing too. and just about in the center of that bell curve of
> difficulty.
>
> joe
>
> Ken Hunter wrote:
>
> > A 10 inch f5-6 is a very DO-ABLE mirror for a first time project. Large
> > enough to be worth something when you are done. Still transportable
without
> > buying a cargo van and fast enough so that you can easily see the
Focault
> > donut when testing. (And faint fuzzies when you are done!)
> >
> > Ken Hunter
> >
> > ----- Original Message -----
> > From: "Charvell" <charvell@sofnet.com>
> > To: <atm@shore.net>
> > Sent: Friday, October 05, 2001 7:59 PM
> > Subject: Re: A Schiefspiegler as first telescope (was Re: ATM 3-Vane or
> > 4-Vane Spiders)
> >
> > >
> > > So a long focal lengh mirror is actually harder to do than a medium
focal
> > > lengh? Am I getting this correctly? Long=hard, medium=easier,
short=very
> > > hard. So where is the very easiest place to start and would a 10" be
OK
> > for
> > > a first time mirror or should I try a smaller? I want the easiest
option
> > to
> > > start with. I don't have anyone I can get to come over and bail me out
:)
> > >
> > > ----- Original Message -----
> > > From: "mjc5" <mjc5@psu.edu>
> > > To: <atm@shore.net>
> > > Sent: Friday, October 05, 2001 6:07 PM
> > > Subject: Re: A Schiefspiegler as first telescope (was Re: ATM 3-Vane
or
> > > 4-Vane Spiders)
> > >
> > >
> > > >
> > > > I suggest the 8 inch f6 or f8. I've made an F10.2 mirror, and it
isn't
> > > > as easy as it may seem at first. A sphere at that length is a
shallow
> > > > creature indeed.
> > > >
> > > > Then if you want to make your Schief, you can apply what you learned
> > > > from your first mirror.
> > > >
> > > > - Mike -
> > >
> > >
> > >
>
>
>